高温条件下膨润土阻滞放射性核素迁移机制研究  

Mechanism for Bentonite Buffers Migration of Radionuclide at High Temperature

作　　者：李伟民[1] 宋功保[2] 孙杰[3] 舒小艳[1] 

机构地区：[1]西南科技大学材料科学与工程学院,四川绵阳621010 [2]西南科技大学国防科技学院,四川绵阳621010 [3]中国工程物理研究院化工材料研究所,四川绵阳621900

出　　处：《中国稀土学报》2010年第2期188-195,共8页Journal of the Chinese Society of Rare Earths

基　　金：863科技计划子课题(2009AA050703);西南科技大学核废物与环境安全国防重点学科实验室资助项目(07JGZB09)

摘　　要：为研究高温条件下膨润土阻滞放射性核素迁移机制,以内蒙古高庙子膨润土为原料,Nd3＋模拟Am3＋,采用高温固态反应方法开展模拟实验。利用X射线荧光、热分析和X射线衍射对内蒙古高庙子膨润土和模拟固化体的元素含量、相转变温度、物相和结构进行了分析,同时利用R ietveld方法对固化体进行了结构精修。研究结果表明：内蒙古高庙子膨润土主要矿物组成为蒙脱石和石英,且含有少量的方石英和长石,在1000℃以下,膨润土中未发现新物相生成。1000℃以上,固化体中的蒙脱石发生固相转变反应形成堇青石相,Nd3＋以替代Mg2＋的形式固化在堇青石结构中,形成[NdO6]八面体,导致a值减小,b,c和V值增加,膨润土对放射性核素Am3＋的模拟核素Nd3＋固容量为0~8%（质量分数）,最佳固容温度为1150℃。In order to investigate bentonite for immobilization of nuclide,trivalent neodymium（Nd3＋） was used to substitute for trivalent americium.The simulated experiments were conducted by using bentonite from Gaomiaozi,the inner mongolia autonomous region as starting materials in the course of high temperature synthesis.The contents of element,phase inversion temperature,the consists of phase,and the structure were characterized by X-ray fluorescence spectrometry（XRF）,thermo gravimetry-differential thermal analysis and X-ray diffraction（XRD）.The results indicated that the montmorillonite and quartz were main phases,together with a bit of cristobalite and feldspar phases in bentonite from Gaomiaozi.No new phase was found under 1000 ℃,but the new phase cordierite was generated in the solid-state reactions when temperature was higher than 1000 ℃.In the crystal lattice of cordierite Mg was substituted by Nd,the new octahedron resulted in decrease for the value of a,as well as increasing of the value of b,c and V,which the highest immobilization content was 8%,and optimal immobilization temperature was 1150 ℃.

关 键 词：膨润土 放射性核素 RIETVELD精修 迁移 机制 稀土 

分 类 号：X591[环境科学与工程—环境工程] X705